DE1302391B - - Google Patents

Description

Certain chemical reactions in the gas phase require a fairly low pressure, or, a low temperature, in order to produce a satisfactory yield to proceed. This is the case, for example, with the cracking of hydrocarbons, where 5 the reactions proceed with an increase in volume and the products are unstable at high temperature. The same goes for the synthesis of ozone from oxygen, since ozone is only present in high concentrations is stable at a lower temperature. When the reactions are endothermic, as is the case with the two mentioned Reaction types is the case, is carried out by supplying the necessary for the reaction Energy as well as complicated by the need to sharply and suddenly increase the obtained products cool. These processes can be carried out batchwise or in chemical reactors take place in several stages, with large amounts of gas having to be treated in each stage. So requires in the synthesis of ozone the low yield of that carried out at ordinary temperature common processes a continuous separation and recycling of the unconverted oxygen, its storage in high concentration and at low temperature costly and with the risk of explosion connected is.

The invention is based on the object, the processes mentioned continuously and in one perform a single device while avoiding the disadvantages of the previous method.

The solution to this problem is a process for the continuous implementation of chemical reactions by means of electrical discharges in one containing the gaseous reaction components Gas flow, which is characterized in that at least one point is at supersonic speed Moving gas stream triggers an electrical discharge at reduced pressures and temperatures due to adiabatic relaxation. This process has one or more of the following characteristics:

a) the discharge consists of at least one arc;

b) the discharge consists of at least one glow discharge;

c) a substance that is able to react with the products formed is transferred to the place of reaction, d. H. led into the immediate vicinity of the electrical discharge.

5 "

It is true from the German patent specification 261102 a method is already known in which an electrical discharge is carried out through a cooling chamber leading nozzle-shaped opening through which gases flow, the gases with high Speed into the refrigerator compartment. The converging one used in this method However, the nozzle never allows a gas flow speed of more than the speed of sound; because a supersonic flow is only possible with the use of converging-diverging ones Nozzles possible. Surprisingly, however, such converging trends have never been seen before Nozzles for the continuous implementation of chemical reactions by means of electrical Discharges used in a gas stream containing the gaseous reaction components.

45 The particular advantage of the method according to the invention, in which an electrical discharge is now triggered in the gas flow moving at supersonic speed at pressures and temperatures reduced by adiabatic relaxation, is that due to this supersonic speed at which the formed during the discharge Substances are sucked off very quickly, in connection with the adiabatic expansion of the gases to be treated the possibility of recombinations of the substances formed by the discharge with one another as a result of the lowering of the molecular movement of the gas and the likelihood of the molecules touching one another is reduced considerably and thus the yield products to be obtained in this process is significantly increased compared to previously known processes.

The invention also relates to a device for carrying out the method described. This device is essentially characterized by a with a voltage source in Connecting supersonic reaction tube with narrowing to the neck-shaped intermediate part Inlet part and then the widening outlet part with a subsequent manifold as well as an electrical discharge extending through the reaction tube and at least in it inside the outlet part of the reaction tube, also connected to a voltage source standing electrode and finally one surrounding the exit part of the reaction tube and at its outlet opening to the manifold reduced a closed space by its suction effect Pressure forming vacuum chamber.

This device has one or more of the following characteristics:

a) the electrode is arranged axially in the supersonic reaction tube;

b) the electrode arranged axially in the reaction tube is via the exit of the reaction tube also extended in such a way that an electrical discharge takes place in the outlet nozzle;

c) the outlet nozzle has a part in which there is supersonic speed and in which the electrical discharge takes place;

d) the outlet nozzle has a part in which there is supersonic speed, and the electrical discharge takes place in the subsonic area of the outlet nozzle;

e) the electrode is hollow and is used to introduce a substance that is associated with the products formed is to be implemented;

f) the hollow electrode has an inner profile in the form of the reaction tube, around the gaseous reactants to be able to supply under aerodynamic conditions which correspond to the conditions prevailing at the outlet of the electrode;

g) the hollow electrode has side openings provided for injecting the gaseous substance;

h) the hollow electrode is provided with at least one wall part made of porous material;

i) the outlet nozzle is equipped with a system

3 4

see that at least one electron lens is extended into the outlet nozzle. if holds that a constriction in the outlet nozzle verdes the electrode into the outlet nozzle ionized by the electrical discharge is prolonged, the gas flow can be supersonic gas flow causes. speed inside this nozzle for one

5 persist for a certain distance, with the shock wave

It can thus be seen that an effort is made on the cylindrical part of the outlet connection

continuous strong cooling and significant localization. Since the cross section of the outlet

Liche pressure reduction in the gas flow to achieve before the nozzle is slightly larger than the cross section of the

therein the desired reaction through the electrical outlet of the reaction tube, is the product P ■ d

Discharge is carried out. The supersonic range io is also somewhat larger here, and theoretically it should

enables this sharp decrease in temperature. no discharge takes place here. Indeed can

As is well known, the discharge at the pipe outlet can occur with the gas flow in the sound if it is strong enough

range a temperature below 0.8 T can be achieved, ionize the gas, whereby the gas becomes conductive,

where T is the absolute temperature of the gas at the. The electrical discharge can vary between

Pipe entry is. In the method according to the invention 15 continue the electrode and the wall of the outlet nozzle,

can temperatures of 0.3 T or even more where the gas has a second discharge inside the

lower temperatures can be reached. This allows you to experience the outlet nozzle, the length of which

it is possible, based on the surrounding environment, can be designed to be extremely high.

temperature, at about products - get 200 ⁰ C. The if the discharge is strong enough also remain

The temperature decrease depends only on the ratio of the 20 gases after their recompression across the board

Pressures at the inlet and outlet of the reaction tube ionize the shock wave, and the discharge can itself

from and is practically only persisted by the liquefaction beyond the shock wave when the

the temperature of the gases at the local pressure at the central pipe electrode is sufficiently extended,

limited exit. This secondary discharge is much less intense,

The gases must be as fast as possible, but the reaction can be very long. The main discharge

flow through the zone, because if the inlet at the outlet of the pipe is too long, then in all cases

The effect of the electric discharge is on the products because it enables the secondary discharges

it formed could destroy again. by ionizing the gases it generates.

The supersonic speed allows very high electrical energies when discharging

high circulation speeds and thus very short 30 or occur during the discharges or when the

To achieve transit times of the gas molecules. strong change in chemical reaction

If, in addition, a low pressure produces a specific mass to achieve a specific mass, be it by changing

a good electrochemical efficiency of the tion of the temperature or by changing the

Unloading is necessary, it can easily be in excess volume, the outlet nozzle or collector can

reach the sound range. 35 is no longer subject to these new operating conditions.

The supersonic speed range requires adjustment. The pressure in the relaxation chamber

mandatory the presence of a recompression - in this case increases and lifts the operational readiness

the shock wave to get back into the subsonic shaft of the reaction tube. Since it is difficult

speed range. The presence - a change in the cross section of the outlet nozzle

This shock wave limits the discharge in the 40 depending on the flow conditions

The flow space, because the one through the shock wave, has to be made via an outlet nozzle

The sudden increase in pressure called for allows one to have a maximum cross-section and on the

no more discharge. Acting gas flow so that it is more or less

This property enables the discharge to be constricted. On the other hand, if the flow is restricted to a very narrow space. If 45 fluctuations with a certain periodicity, which is P the pressure in the height of a cross-section of the case of a gas that is exposed to an alternating current tube and d the distance between the electrode, one must on the gas and the tube wall is, then the product P · d has the same frequency with which the change takes place its smallest value at the exit of the expanding specific mass, and the required part of the reaction tube, if this is functionally ready with a certain phase shift is. The electrical discharge takes effect, which corresponds to the time that a unit always takes place at the exit of the reaction tube and the volume of the gas needs to extend the distance between the main discharge lying above the shock wave and the point where the one part of the Outlet nozzle, when the shock wave constriction of the gas flow occurs, to go through is intense enough. Since the gas molecules are ionized by their passage through the downward-lying end of the electrode, a discon- tinuity in the flow is possible inclined swirling effect. The ionized gas can be viewed as a current from the shock wave that electrically charged particles attach to the end of this electrode. In practice, the electric discharge 60 which is applied to the space between the exit plane of the pipe with an electric or magnetic field takes place. Such electron lenses are already and the shock wave one. known and used to focus electrically

In certain cases, however, it may be advantageous or charged particles, e.g. B. in electron microscopes,

be necessary, the discharge is needed on a gas mixture. An electrostatic field can pass through

let it work for a certain period of time. 65 an electron lens can be created that has the shape

It is possible to have the discharge in the previously through a cylinder that surrounds the outlet nozzle

the discharge of ionized gas mixture is arranged on the outside of the tube or on its inner surface and on

occurs by maintaining a certain potential relative to the mass of the electrode axially

Rcaktionsrohrcs is brought. The potential can be maintained, as these disrupt the gas flow

divisions that are going to have a powerful effect. Despite the changing distance between

however considerable and practical is the electron vision of the electrode and the tube walls

lens difficult to use. A magnetic field stabilizes the discharge, i. H. the arc

can be generated by an electromagnetic lens 5 or the glow discharge, at the end 7 of the

consisting of a winding, the axially tending part, because this is where the pressure is

is placed around the outlet nozzle and is lowest from one. An alternating current is applied to the electrode

Current flows through, the strength of which depends on an open circuit voltage of several thousand

speed is regulated by the desired effect. If volts to the reaction tube are known and not shown

an alternating current is supplied to the electrode, is supplied in a positional manner. The open circuit voltage of the

can use an AC voltage power source depends on the type and pressure of the electron lens

or with an alternating current of the same frequency gas as well as the dimensions of the pipe and

are fed, the opposite of the current in the amount of gas to be treated.

Discharge shifted by an amount in phase The frequency can vary depending on the

can be chosen from the dimensions of the chemical reaction desired,

direction and speed of it through- In the extension of the tube 1 and in its

flowing gases depends. Axis is one of the with a certain distance

In the following, simple examples of recompression service manifolds 13

several embodiments of the method according to (outlet nozzle) arranged, which has a short, itself

of the invention as well as several embodiments of the 20 narrowing part 14, a cylindrical neck 15,

Device according to the invention in connection whose diameter is slightly larger than the diameter

explained with the drawings. knife of the outlet of the reaction tube, and a

F i g. Fig. 1 shows schematically in axial section a widening part 16 which leads to the open air

Reactor according to the invention in the form of an overflow. Both the outlet nozzle 13 and the

sound tube with axial hollow electrode; ■ 25 reaction tube 1 can with the help of known form

F i g. 2 is a graph showing the my being calculated showing its geometric out-of-area the partial oxidation of the methane visualization depending on the desired markings; 'paint set. In the outlet nozzle, the

F i g. 3 is a longitudinal section through a reaction rate of the gas flow during its pressure

device according to the invention, in particular 30 and its temperature rise,

to carry out the partial oxidation of methane The pipe 1 and the manifold 13 are through

is used; a relaxation chamber 17 connected to one another

F i g. Figure 4 is a schematic of a device associated with those in whose walls 18 they are screwed. the

a hollow electrode with the inner profile in the form of chamber 17 plays an important role for the radio

of the reaction tube is provided and when the readiness of the reaction tube at the initiation

ionized gas flow with an electromagnetic operation of the device and guaranteed

Lens is constricted. stable operation due to their volume. At the in-

In Fig. 1, a supersonic pipe 1 is shown, the operation of the device enables the entaus a narrowing inlet part 2, a tension chamber 17 as a result of the suction through the neck 3 and an expanding outlet part 4 40 the outlet nozzle 13 is maintained at whose inlet the gas through a sufficiently low pressure at the outlet of the cylindrical part S is performed. That through a widening part 4 of the pipe. During the BeRohr 6 introduced into the device gas expands drive, the chamber 17 maintains stable operation of the expanding part 4 and reaches the entire device by raising the end 7 of this part to its lowest temperature and 45 raising the operational readiness of the pipe by its lowest pressure as well as its highest accidental pressure increase in the expanding speed. For example, at the inlet to part 4 avoids that could occur when the pipe 6 the pressure of the gas is 5 kg / cm ² and the passage between the outlet of the expanding ratio of pressures before and after the expansion of the part 4 of the pipe and the narrowing about 50. This causes sufficient cooling 50 of part 14 of the outlet connection with the atmosphere of the gas. The relaxation is due to the pressure connected
high velocity of the gases, which have a heat- Below two types of reactions are restricted to exchange with the pipe, practically described adia- that using the described batic. In the axis of the reaction tube a device is carried out and an Aus-Hohlclektrode 8 is arranged, which through insulating webs 9 55 guide form of the method according to the invention and 10, which are mounted in the cylindrical part 5, represent.

is held in place. The electrode is tight methane is introduced under a pressure of 5 kg / cm ² into the reaction tube in the cylindrical part 5 through an insulating stopper and undergoes an adia-11 introduced, which at the end of the cylindrical part 5 bulges relaxation on the tube already described held by a threaded piece 12 60 ways. The methane molecules are broken down under the effect of the electrical discharge,

The fact that the electrode is hollow, and the products obtained, combine the two advantages with it, that optionally one with the formation of acetylene and hydrogen. This product, which reacts with the reaction products at the end of the reaction, is favored by the low pressure at the outlet of the tube, through its axis 65 the reaction tube passes, ie at the point where the electrical discharge can be introduced and its rigidity takes place ,
is improved. This is necessary because the electrode is not sufficient to increase the gas flow

7 8

further reaction of the acetylene-water formed or according to the reaction
to effect a mixture of substances, so that these products

CJ3 CH + HO -> 2 HCHO + HO obtained immediately at the exit of the reactor,

will. 'ι ι ^{2 2} '

The invention is also applicable to most gas 5 q q

shaped hydrocarbons applicable when s. s

it is a matter of an increase in volume O
to carry out the ongoing chemical reaction.

The second example concerns the production of in the presence of water.

Ozone from gaseous oxygen. The oxygen ίο

is introduced in the manner described under a pressure The partial oxidation of methane is a classic of 6 kg / cm ² . As a result of the reaction taking place in the tube, which can be carried out by finding an adiabatic relaxation, the methane flow falls into an oxygen flow, which has a temperature and pressure of the oxygen considerably. contains a certain proportion of ozone, is introduced. The products that take place in the gas stream at low temperatures are obtained, depending on the reaction conditions, on the formation of formaldehyde, methanol and formic acid in large amounts and in high concentrations, in different proportions. However, this persists as long as the temperature of the gas - the concentration range of the ozone in the oxygen stream - does not rise again to an excessive extent. substance in which this reaction takes place, within the low temperature of the gas at the point where very narrow limits are kept,
The electrical discharge is taking place. In FIG. 2, a diagram of this area is shown that a high degree of efficiency of the distortion can be achieved. In area I, the reaction is extremely charged, that is, most of the reaction is slow, its speed is almost zero, electrical energy is converted into chemical energy and in area III there is complete oxidation of the ring part being converted into heat. The high methane without the formation of intermediate products at the speed of the gas flow at this point strong heat development, which is often harmful to the equipment, the good efficiency of the discharge is instead. It can be seen that the condition that the ozone formed is quickly discharged rich II, ie the partial oxidation, with increasing ozone and a noticeable reheating of the gas 30 concentration in the oxygen becomes increasingly narrow, so by the electrical discharge that one under the usual conditions of growing heat is avoided. It is evident that recompression concentrations and costly recycling of the gases are required in order for them to work to the atmosphere of the unreacted oxygen.
or in a room in which a certain pressure 35 In contrast to this, it is possible to be able to dissipate the partial oxide. As a result, the ion of methane is brought back close to the normal charge with the help of an electrical discharge temperature of the gas, which is brought during a certain initial value and consequently the time, for example 100 seconds, quickly decomposes on a mixture of ozone contained in it. So it is acted by methane and oxygen
expedient to use the ozone immediately after its 40 In Fig. 3, a device according to the invention is to use continuously. dung for carrying out the partial oxidation of It is assumed that the ozone formed represents methane. This device, which is very similar to that shown in partial oxidation of ethylene to formaldehyde shown in FIG. 1, contains a used. For this purpose, the ethylene supersonic tube 1, one of the recompression diem with the help of the hollow electrode near the 45 nenden collecting pipe 13 and a vacuum-expanding outlet part of the reaction tube at chamber 17. The tube 1 consists of the cylindrical point where the ozone concentration can be seen part 5, a narrowing part 2 and is highest. The ozone combines immediately in a widening part 4. The collecting pipe with the ethylene to form ethylene ozonide 13 comprises a tapering part 14, a rather long cylindrical part 15 according to reaction 50, the diameter of which in this case is equal to the diameter of the

CH ₂ = CH, + O. _t - »- CH ₂ - CH ₂ outlet of the tube 1, and an expanding one

I I Part 16. The converging part 14 takes place during

Q Q of operation does not matter if the pipe

s. / 55 is ready for operation, however, it facilitates its commissioning.

O would take at the beginning by putting it in the vacuum chamber 17 sucks in gases contained. A hollow

This ethylene ozonide can then be on the electrode 8 is in the axis of the reaction tube

Decompose reactor outlet, according to the reac- arranged and in the manifold up to the

tion 60 expanding part 16 out. The electrode that

by insulating struts 9 and 10 in the supersonic range

CH ₂ - CH ₂ - * - 2 HCHO + 1/2 O ₂ the gas flow is kept hollow to methane

I I to be able to introduce into the manifold. to

O O for this purpose the electrode is closed at the end,

\ _n / ⁶ 5 during the cylindrical part of the collecting

⁰ nozzle lying part with side openings 8 a

is provided.

in the absence of water The reaction tube 1 is oxygen under a

9 ίο

Pressure of about 6 kg / cm - with the help of an inlet - thus less than -200 ° C. The axially extending tube 6 supplied. When the tube is operational electrode 20 is connected to an AC transformer is, there is a pressure of 21 connected to its outlet, which has a high voltage of about Vio atmosphere or less. This low pressure supplies 2000 V and through a standard 50 Hz network remains in place until the shock wave, where the gas impact 5 is fed. An electrical discharge, its lei-like is re-sealed. This shock wave, which is stung 20 kW, takes place on the route between by pressing methane into the area above the exit level of the pipe and the area at the entrance level moving flow in the cylinder inlet of the manifold in the converging part thical part of the outlet connection caused forming shock wave instead. The profile of the electrode is a sloping, swirling shock io 20 is inside in the form of a widening nozzle shaft formed at the first supply ports 8a to prevent the introduction of ethylene under arises. Your approximate location is to be made by aerodynamic conditions at 19 dashed line indicated. correspond to those of the ozone at the point of supply. There

The electrode 8 and the reaction tube 1 are to be supplied through the electrode ethylene is her connected to a generator which fills a stream 15 outflow area with ethylene, so that the surge generates high voltage of about 5000 volts. It doesn't necessarily take place immediately at the end of the wave a discharge in the supersonic range of the gas flow electrode occurs.

between the end of the reaction tube and the The ethylene immediately takes the formed

Shock wave instead. This discharge is strong enough to cause ozone to rise, forming ethylene ozone

to ionize the oxygen stream, but to a known 20

Way (for example by switching a counter- CH ₂ —O ₃ —CH ₂ ,
Stand in series with the high voltage generator)

deliberately so limited that the concentration of this subsequently turns into a mixture of form ozone not sufficient to oxidize the methane, aldehydeHCHO and oxygen or - if the d. This means that in the area T or, if necessary, in the area II 25 decomposition takes place in the presence of water - of of the diagram of FIG. 2 cherishes. Formaldehyde and hydrogen peroxide decompose.

Since the oxygen through this first discharge will have a high yield, e.g. B. has been ionized by at least 60% if a second discharge is desired in the reaction, the strength of the shock wave between the electrode and the change in specific mass must be taken into account the reaction occurs due to the high one it a voltage difference with the help of an ozone content of the oxygen. It is therefore necessary (also not shown) to have high voltage to subject the gas flow in the manifold to the opening generator. The effect of this second discharge is that it is constantly aerodynamic, i.e. in the mixture of ionized acid conditions after the reaction, substance and methane take place and can be due to the large length of the cylindrical part on the ionized gas flow of the collecting with an electron lens, which consists of a nozzle and the relatively low speed winding 22 of 20 turns from isolated digkeit of the gas flow at this point about Vioo Se copper braid of 4X5 mm and the collecting act on a volume unit of the gas. surrounds nozzle, the inner diameter of which is 2 cm. The winding is made of an alternating current mixture of formaldehyde HCHO, methanol at the same frequency as the CH _a OH and formic acid HCOOH fed to the arc, which contains about current and a maximum strength of 200A 80% formaldehyde. The amount of methane blown through the transformer 21 via the hollow electrode is also a voltage-lowering transformer 23, which is high or slightly higher than the amount of oxygen blown through the tube 6, which emits a voltage between 0.5 and 1 V so that it is delivered. The escaping gases flowing in the magnetic lens 22 no longer have to escape free oxygen, based on the current in the arc. This device enables the handling in the phase of about 1000 seconds or 18 ° of about 36 m ^{3 of} oxygen per hour to be shifted backwards in order to achieve the throughput of an effective total power of about 50 kW. so transit time of the products between the arc and

Another example to be taken into account is the oxidation of the ethylene manifold. Since the Imlcn C ₂ H ₄ with ozone to formaldehyde HCHO is negligible with respect to the resistance of the winding 22 with respect to its resistance using an oxygen-ozone mixture, this phase shift of high ozone concentration, in Fig. 4 device shown received 55 exercise of an iron core is adjustable, causes
is described. This device also consists of the low voltage supplied to the lens, like the one described in the previous example, in accordance with the reaction conditions, by means of a supersonic pipe 1, one of the servo devices, the manifold 13 serving to recompress a transformer 25, with a variable transmission ratio, such as a vacuum chamber 17 and a hollow electrode 60 acts that the pressure in the negative pressure chamber 20 of a special kind. Oxygen in the tube 1 is kept constant below 17. For this purpose, a pressure of 10 kg / cm ^{2 is added} through the pipe 6 to the pressure ρ in the chamber 17 with a class. Under steady-state conditions, there is measured at the diaphragm manometer 26, which is coupled with the exit of the widening part of the reaction to an electromagnetic transducer 27 with piping and in the vacuum chamber 17 a pressure 65 slidable magnetic core. This wall on the order of 0.1 atm. The flow is primarily through a 50 Hz current of a flowing oxygen amount of 18 m ^s / h. The winding of a transformer 28 is fed, and its temperature of oxygen at this point is two secondary windings form with two resistors

would 29 α and 296 be a Wheatstone bridge, which with the help of the two resistors 29 a and 29 b mentioned at the desired pressure /? is brought into balance. Any change in the pressure ρ causes a displacement of the magnetic core of the transducer 27 and removes the balance of the bridge. The excess emf, the phase and amplitude of which indicate the direction and magnitude of the pressure deviation, is amplified by a magnetic amplifier 30 of known type and impressed on the control phase of a two-phase motor 31, the reference phase of which is fed by a winding of the transformer 28. The motor 31 drives the regulating transformer 25 via a reduction gear 32 and adjusts the current in the winding 22 so that the pressure ρ is kept at its prescribed value, determined by the equilibrium of the Wheatstone bridge.

The current in the winding 22 builds up a magnetic field that has a variable contraction of the gas flow in the manifold.

Claims (6)

Patent claims: 1. Process for the continuous implementation of chemical reactions by means of electrical Discharges in a gas stream containing the gaseous reaction components, thereby characterized in that one is at least one point at supersonic speed moving gas flow at reduced pressures and temperatures due to adiabatic relaxation triggers. 2. Apparatus for performing the method according to claim 1, characterized essentially through a supersonic reaction tube connected to a voltage source with the entry part narrowing to the neck-shaped intermediate part and then widening Exit part with a subsequent collecting pipe and one that extends through the reaction tube and at least in it, the electrical discharge within the exit part of the Reaction tube triggering, also connected to a voltage source electrode and finally one which surrounds the outlet part of the reaction tube and is attached to it The outlet opening to the manifold reduced a closed space due to its suction effect Pressure forming vacuum chamber. 3. Apparatus according to claim 2, characterized by an axially arranged in the reaction tube Electrode. 4. Apparatus according to claim 2 or 3, characterized through a through the outlet part of the reaction tube and into the manifold protruding electrode. 5. Apparatus according to claim 2 to 4, characterized by a hollow electrode for insertion gaseous reaction components. 6. Apparatus according to claim 2 to 5, characterized by a constriction of the ionized gas flow arranged in the collecting nozzle effecting electron lens. For this purpose 2 sheets of drawings